Pump drive head with stuffing box

Abstract

A pump drive head for a progressing cavity pump comprises a top mounted stuffing box rotatably disposed around a compliantly mounted standpipe with a self or manually adjusting pressurization system for the stuffing box. To prevent rotary and vertical motion of the polish rod while servicing the stuffing box, a polished rod lock-out clamp is provided with the pump drive head integral with or adjacent to a blow-out-preventer which can be integrated with the pump drive head to save space and cost. A centrifugal backspin braking system located on the input shaft and actuated only in the backspin direction and a gear drive between the input shaft and output shaft are provided.

1. A drive head assembly for use to fluid sealingly rotate a rod extending down a well, comprising;
 a housing having upper and lower openings for receiving said rod therethrough;  
 a rotatable sleeve adapted to concentrically receive a portion of said rod therethrough, said sleeve being rotatably mounted in said housing and having an upper end passing through said upper opening to extend outwardly of said housing;  
 a prime mover drivingly connected to said sleeve for rotation thereof;  
 means disposed on said upper end of said sleeve for drivingly connecting said sleeve to the rod; and  
 seal means within said sleeve to prevent the escape of well fluids, wherein said means for drivingly connecting said sleeve to said rod are removable from said upper end of said sleeve for servicing of said seal means without removal of said drive head assembly from the well.  
 
   
   
     2. The drive head assembly of  claim 1  further comprising a tubular standpipe concentrically mounted within said sleeve in annular spaced relation defining a first annular fluid passageway between said standpipe and said sleeve and a second annular fluid passageway between said standpipe and said rod, said second passageway being in fluid communication with wellhead pressure in said well during normal operations. 
   
   
     3. The drive head assembly of  claim 2  wherein said seal means are disposed between said first and second passageways permitting the maintenance of a fluid pressure differential therebetween. 
   
   
     4. The drive head assembly of  claim 3  including means for maintaining the fluid pressure in said first passageway in excess of wellhead pressure in said second passageway. 
   
   
     5. The drive head assembly of  claim 4  wherein said seal means are disposed in said first passageway. 
   
   
     6. The drive head assembly of  claim 5  wherein said seal means are compressively loaded in said first passageway for enhanced sealing. 
   
   
     7. The drive head assembly of  claim 4  wherein said means for maintaining the fluid pressure in said first passageway comprises a fluid pump and a fluid conduit for the delivery of pressurized fluid from said pump to said first passageway. 
   
   
     8. The drive head assembly of  claim 7  wherein said pump is actuatable by said prime mover. 
   
   
     9. The drive head assembly of  claim 7  wherein said means for drivingly connecting said sleeve to the rod comprises a cap member releasably and tightenably connectable to said upper end of said sleeve for rotation therewith, said cap member having a bore for the passage of the rod therethrough, and a rod clamp connected to said cap member for transmitting rotational torque from said cap member to said rod. 
   
   
     10. The drive head assembly of  claim 9  further comprising static seal means disposed in sealing contact around said rod adjacent said upper end of said sleeve. 
   
   
     11. The drive head assembly of  claim 10  wherein said static seal means comprises one or more vertically stacked sealing members and a rigid seal carrier for supporting said seal members about the rod, said seal carrier sealingly occupying the annular space between said sealing members and the inner surface of said upper end of said sleeve. 
   
   
     12. The drive head assembly of  claim 11  wherein said seal means and said static seal means operably function together as a stuffing box for said rod. 
   
   
     13. The drive head assembly of  claim 12  wherein removal of said cap member from said sleeve enables said stuffing box to be serviced without removing said drive head assembly from the well. 
   
   
     14. The drive head assembly of  claim 13  wherein tightening said cap member on said sleeve compressively loads said stuffing box for fluid sealing purposes. 
   
   
     15. The drive head assembly of  claim 13  including means to bias said seal means towards said seal carrier and, in turn, said seal carrier towards said cap member. 
   
   
     16. The drive head assembly of  claim 15  wherein said means to bias press said seal means against said seal carrier and, in turn, said seal carrier against said cap member when the fluid pressure in said first passageway exceeds wellhead pressure in said second passageway. 
   
   
     17. The drive head assembly of  claim 15  wherein said means to bias is a spring. 
   
   
     18. The drive head assembly of  claim 13  including a ring member disposed beneath said seal means to support said seal means in said first passageway. 
   
   
     19. The drive head assembly of  claim 18  including means to bias said seal means against said ring member and to bias said seal carrier against said cap member. 
   
   
     20. The drive head assembly of  claim 19  wherein said means to bias is a spring. 
   
   
     21. The drive head assembly of  claim 15  further including a first upper and a second lower spaced apart bearing hubs, each having a bore formed axially therethrough for rotatably supporting said sleeve therein. 
   
   
     22. The drive head assembly of  claim 21  wherein a lower end of said standpipe is received into said bore in said lower bearing hub for a fluid tight connection between said standpipe's outer surface and said bore, the interior of said standpipe remaining exposed to wellhead pressure. 
   
   
     23. The drive head assembly of  claim 22  further including a labyrinth seal for fluid sealing between said first fluid passageway and said lower bearing hub. 
   
   
     24. The drive head assembly of  claim 23  wherein said labyrinth seal is sealingly biased against an inner surface of said first fluid passageway and a contiguous surface of said lower bearing hub. 
   
   
     25. The drive head assembly of  claim 24  wherein said labyrinth seal includes a plurality of apertures formed axially therethrough for respective fastening members adjustably connecting said labyrinth seal to said contiguous surface of said lower bearing hub. 
   
   
     26. The drive head assembly of  claim 25  wherein the diameter of said apertures exceeds the diameter of said fasteners permitting said labyrinth seal to move in the horizontal plane relative to said contiguous surface of the lower hub for self alignment of said labyrinth seal to said inner surface of said first fluid passageway. 
   
   
     27. The bearing head assembly of  claim 26  including an O-ring seal between said labyrinth seal and said contiguous surface of said lower bearing hub for additional sealing therebetween. 
   
   
     28. The drive head assembly of  claim 21  wherein said prime mover is drivingly connected to said sleeve by gears. 
   
   
     29. The drive head assembly of  claim 28  wherein said gears comprise a drive gear connected for rotation to a drive shaft extending from said prime mover, and a driven gear fixedly connected to said sleeve for transferring rotational torque from said drive gear to said sleeve. 
   
   
     30. The drive head assembly of  claim 29  wherein said inner surface of said first fluid passageway is defined by one or more of the inner surface of said sleeve, said driven gear, a bearing member rotatably supporting said sleeve or an extension member connected to said sleeve. 
   
   
     31. The drive head assembly of  claim 29  wherein said housing supports said prime mover and said first and second bearing hubs thereon, and encloses said drive shaft and said drive and driven gears therein. 
   
   
     32. The drive head assembly of  claim 4  including adjustable valve means for controlling the pressure of fluid in said first fluid passageway. 
   
   
     33. The drive head assembly of  claim 32  wherein the pressure of fluid in said first fluid passageway is maintained in the range of 50 to 500 psi in excess of wellhead pressure in said second fluid passageway. 
   
   
     34. In a stuffing box for sealing the end of a rotatable rod extending from a well bore, the improvement comprising:
 a first fluid passageway disposed concentrically around at least a portion of the rod passing through the stuffing box;  
 a second fluid passageway disposed concentrically inside said first passageway, said second passageway being in fluid communication with wellhead pressure during normal operations;  
 said first and second passageways being in fluid communication with one another and having seal means disposed therebetween to permit the maintenance of a pressure differential between them; and  
 means to pressurize fluid in said first passageway to a pressure in excess of wellhead pressure to prevent the leakage of well fluids through said stuffing box.  
 
   
   
     35. The stuffing box of  claim 34  including means to normally bias said seal means in opposition to wellhead pressure in said second passageway. 
   
   
     36. The stuffing box of  claim 35  wherein said seal means are disposed in said first passageway between said means to bias and a seal retaining member. 
   
   
     37. The stuffing box of  claim 36  wherein said means to bias comprise a spring to act with or without pressure in said first passageway to oppose wellhead pressure in said second passageway. 
   
   
     38. The stuffing box of  claim 34  further comprising an outer axially disposed tubular sleeve disposed around a tubular standpipe concentrically mounted within said sleeve in annular spaced relation to said sleeve and the rod, the annular space between said sleeve and said standpipe defining said first passageway and the annular space between said standpipe and the rod defining said second fluid passageway. 
   
   
     39. The stuffing box of  claim 38  wherein said sleeve is supported for rotation and is drivingly connected to said rod for rotation thereof. 
   
   
     40. The stuffing box of  claim 39  wherein said sleeve is supported for rotation by a housing having vertically aligned upper and lower openings for receiving said rotatable rod therethrough. 
   
   
     41. The stuffing box of  claim 40  wherein said sleeve has an upper and a lower end, being adapted for a releasable and tightenable connection to a cap member that closes said upper end around the rod. 
   
   
     42. The stuffing box of  claim 41  wherein said upper end of said tubular sleeve extends through said upper opening to extend upwardly and outwardly from said housing. 
   
   
     43. The stuffing box of  claim 42  additionally comprising static seal means disposed in sealing contact around said rod in said upper end of said tubular sleeve. 
   
   
     44. The stuffing box of  claim 43  wherein said static seal means comprise one or more vertically stacked sealing members and a rigid seal carrier for supporting said seal members about the rod, said seal carrier sealing occupying the annular space between said sealing members and the inner surface of said upper end of said tubular sleeve. 
   
   
     45. The stuffing box of  claim 44  wherein said cap member is releasable from said upper end of said tubular sleeve for servicing of said stuffing box from outside said housing. 
   
   
     46. The stuffing box of  claim 34  wherein said means to pressurize fluid in said first passageway comprise a fluid pump and a fluid conduit for the delivery of pressurized fluid from said pump to said first passageway. 
   
   
     47. The stuffing box of  claim 46  wherein said pump is actuatable by a prime mover, said prime mover also being drivingly connected to said sleeve for rotation thereof, said sleeve in turn being drivingly connected to said rotatable rod so that rotation of said sleeve by said prime mover causes rotation of said rod. 
   
   
     48. A drive head for use with a progressing cavity pump in an oil well, comprising:
 a drive head housing;  
 a drive shaft rotatably mounted in said housing for connection to a drive motor;  
 an annular tubular sleeve rotatably mounted in said housing and drivingly connected to said drive shaft;  
 a tubular standpipe concentrically mounted within said sleeve in annularly spaced relation thereto defining a first tubular fluid passageway for receiving fluid at a first pressure and operable to receive a polished rod therein in annularly spaced relation defining a second tubular fluid passageway exposed to oil well presure during normal operation;  
 seal means disposed in said first fluid passageway;  
 means for maintaining the fluid pressure within said first fluid passageway greater than the fluid pressure in said second fluid passageway; and  
 means for releasably drivingly connecting said sleeve to said polished rod received in said standpipe.  
 
   
   
     49. A drive head as defined in  claim 48 , further including a centrifugal backspin retarder coupled to said drive shaft for reducing reverse rotation of said sleeve. 
   
   
     50. In a drive head for rotating a rod in a well having a housing for fluid sealingly receiving the rod therethrough, said housing having a lower end and an upper openable end, the improvement comprising a stuffing box for said rod integrated into said upper end of said housing to enable said stuffing box to be serviced by opening said openable upper end of said housing, without removing said drive head from the well. 
   
   
     51. In a drive head as defined in  claim 50  wherein said stuffing box seals said rod against the pressure of fluid in the well, further including a fluid pump for pressurizing said stuffing box. 
   
   
     52. In a drive head as defined in  claim 51 , maintains an uphole side of said stuffing box at a higher pressure than a downhole side thereof to limit leakage of fluid from said well bore. 
   
   
     53. A drive head with a prime mover for rotatably driving a polished rod in a progressing cavity pump well, including:
 a housing with upper and lower openings for receiving the polished rod therethrough;  
 a tubular drive sleeve rotatably mounted in said housing for axially supporting and rotatably driving said polished rod, said drive sleeve having an upper end extending outwardly of said housing through said upper opening therein;  
 releasable connecting means accessible from outside of said housing for drivingly connecting said upper end of said drive sleeve to said polished rod;  
 a stuffing box to seal said rod against the pressure of fluid in said well disposed in said tubular drive sleeve, said stuffing box being accessible for servicing from outside of said drive head upon removal of said connecting means from said upper end of said sleeve.  
 
   
   
     54. A drive head as defined in  claim 53 , said upper end of said drive sleeve being threaded; said releasable connecting means including a threaded cap member for threadedly engaging said threaded drive sleeve and clamp means for coupling to said threaded cap and to said polished rod. 
   
   
     55. A drive head as defined in  claim 53 , further including:
 a tubular standpipe secured to prevent axial displacement and rotation of said standpipe relative to said housing;  
 said standpipe being disposed within said drive sleeve in annularly spaced relation thereto for generally concentrically receiving said polished rod therethrough in annularly spaced apart relation;  
 rotary sealing means disposed between said standpipe and said drive sleeve to prevent the flow of well fluids into the annulus between said drive sleeve and said standpipe; and  
 static sealing means disposed between said drive sleeve and said polished rod to prevent the escape of well fluids between said drive sleeve and said polished rod.  
 
   
   
     56. A drive head as defined in  claim 55 , wherein said standpipe, said drive sleeve, said rotary sealing means and said static sealing means operably function together as said stuffing box for said polished rod. 
   
   
     57. A drive head as defined in  claim 56 , further including pressurization means to apply a fluid pressure in excess of well pressure against said rotary sealing means. 
   
   
     58. A drive head as defined in  claim 57 , wherein said fluid pressure acts on a lower side of said rotary sealing means against well pressure acting on an upper side of said rotary sealing means. 
   
   
     59. A drive head as defined in  claim 58  further including a first lower sealing means to seal a lower end of said tubular drive sleeve against the pressure of fluid in said annulus between said tubular drive sleeve and said standpipe. 
   
   
     60. A drive head as defined in  claim 59  including a second lower sealing means to seal a lower end of said standpipe to prevent well fluids from escaping into said annulus between said tubular drive sleeve and said standpipe. 
   
   
     61. A drive head as defined in  claim 60 , wherein said first lower sealing means comprise a labyrinth seal between said housing and said tubular drive sleeve. 
   
   
     62. A drive head as defined in  claim 61 , wherein said pressurization means includes a source of pressurized fluid and a fluid passage in communication with said annulus between said tubular drive sleeve and said standpipe and between said rotary seal means and said first lower sealing means. 
   
   
     63. A drive head as defined in  claim 62 , wherein said source of pressurized fluid includes a pump driven from said prime mover. 
   
   
     64. A drive head as defined in  claim 62 , wherein said prime mover is a hydraulic motor which operates to rotate said polished rod and pump said pressurized fluid. 
   
   
     65. A drive head as defined in  claim 59 , wherein said lower end of said standpipe is compliantly secured relative to said housing to minimize misalignment of said standpipe relative to said rotary sealing means. 
   
   
     66. A drive head as defined in  claim 55 , said static seal means including one or more axially stacked sealing members and a rigid seal carrier for supporting said sealing members about said polished rod, said seal carrier sealingly occupying the annular space between said sealing members and an inner surface of said upper end of said drive sleeve. 
   
   
     67. A drive head as defined in  claim 55 , said rotary sealing means including one or more ring seals, said ring seals rotating with and sealed to said drive sleeve and rotating against and sealing to said standpipe. 
   
   
     68. A drive head as defined in  claim 67 , said ring seals comprising packings, said packings rotating with and sealing to said drive sleeve and rotating against and sealing to said standpipe. 
   
   
     69. A drive head as defined in  claim 68 , further including spring means for compressively loading said packings. 
   
   
     70. A drive head as defined in  claim 69 , further including pressurizing means for maintaining lubricating fluid pressure against said packings above the discharge pressure of fluid in said well. 
   
   
     71. A drive head as defined in  claim 70 , said pressurizing means including lower rotary sealing means between said housing and a lower end of said drive sleeve to form an annular fluid chamber between said drive sleeve and said standpipe below said packings and above said lower rotary sealing means; and
 fluid communication between said annular fluid chamber and a pressure source for said lubricating fluid.  
 
   
   
     72. A drive head as defined in  claim 71 , wherein said lower rotary sealing means comprise a labyrinth seal between said housing and said drive sleeve. 
   
   
     73. A drive head as defined in  claim 72 , said pressure source including a pump and a pressure relief valve to regulate said lubricating fluid pressure to said annular fluid chamber. 
   
   
     74. A drive head as defined in  claim 73 , said pump being driven by said prime mover. 
   
   
     75. A drive head as defined in  claim 72 , said pressure source being a hydraulic system including a hydraulic motor, said hydraulic motor being operatively connected to said polished rod for the rotation thereof, and said annular fluid chamber being in fluid communication with said hydraulic system for maintaining said lubricating fluid pressure therein by means of a pressure reducing valve. 
   
   
     76. A drive head for sealing and rotating a polished rod extending into a well bore, including:
 a housing having aligned upper and lower openings therein for receiving the polished rod therethrough;  
 a tubular drive sleeve rotatably mounted in said housing for axially supporting and rotatably driving the polished rod, said drive sleeve having an upper end extending through said upper opening of said housing;  
 a prime mover for rotation of said tubular drive sleeve;  
 means located outside of said housing for drivingly and releasably connecting said upper end of said drive sleeve to said polished rod;  
 a tubular standpipe secured to said housing within said drive sleeve in annularly spaced relation thereto for generally concentrically receiving said polished rod therethrough in annularly spaced apart relation;  
 rotary seal means disposed in an annular space between said drive sleeve and said standpipe, said rotary seal means being exposed on one side thereof to well fluids; and  
 static seal means disposed between said drive sleeve and said polished rod.  
 
   
   
     77. A drive head as defined in  claim 76 , said standpipe being non-rotatably and compliantly secured to said housing to permit said standpipe to accommodate mis-alignment at said rotary seal means. 
   
   
     78. A drive head as defined in  claim 76 , said rotary seal means including one or more ring seals, said ring seals rotating with and sealing to said drive sleeve and rotating against and sealing to said standpipe. 
   
   
     79. A drive head as defined in  claim 78 , said ring seals including packings, said packings rotating with and sealing to said drive sleeve and rotating against and sealing to said standpipe. 
   
   
     80. A drive head as defined in  claim 79 , further including spring means for compressively loading said packings. 
   
   
     81. A drive head as defined in  claim 80 , further including pressurizing means for maintaining lubricating fluid pressure against said packings above the discharge pressure of fluid in said well. 
   
   
     82. A drive head as defined in  claim 81 , said pressurizing means further including lower rotary sealing means between said housing and said drive sleeve forming an annular fluid chamber between said drive sleeve and said standpipe below said packings and above said lower sealing means; and
 fluid communication between said annular fluid chamber and a pressure source for said lubricating fluid.  
 
   
   
     83. A drive head as defined in  claim 82 , said lower rotary sealing means including a labyrinth seal between said housing and said drive sleeve. 
   
   
     84. A drive head as defined in  claim 83 , said pressure source including a pump and a pressure relief valve to regulate said lubricating fluid pressure to said annular fluid chamber. 
   
   
     85. A drive head as defined in  claim 84 , said pump being driven by said prime mover. 
   
   
     86. A drive head as defined in  claim 85  wherein said prime mover is an electric motor. 
   
   
     87. A drive head as defined in  claim 85 , wherein said prime mover is a hydraulic motor that both rotates said tubular drive sleeve and maintains said lubricating fluid pressure in said annular fluid chamber. 
   
   
     88. A drive head as defined in  claim 87 , including a pressure reducing valve disposed between said hydraulic motor and said annular fluid chamber. 
   
   
     89. A drive head for rotatably driving a polished rod in a well, including:
 a housing having vertically aligned upper and lower openings therein for passage of said polished rod therethrough;  
 a tubular drive sleeve rotatably mounted in said housing to concentrically receive said polished rod therethrough;  
 a non-rotatable tubular standpipe concentrically received within said tubular sleeve and sealingly and detachably secured to said housing to define a first annulus between said sleeve and said standpipe and a second annulus between said polished rod and said standpipe;  
 rotary seal means disposed in said first annulus between said standpipe and said drive sleeve in contact with well fluids on one side thereof and with said first annulus on the other side thereof;  
 means for rotating said tubular drive sleeve; and  
 means connecting said tubular drive sleeve to said polished rod for rotation thereof.  
 
   
   
     90. The drive head of  claim 89  additionally including means for drainage of well fluids flowing past said rotary seal means away from said housing. 
   
   
     91. The drive head of  claim 90  wherein said means for drainage include a ring member in said first annulus beneath said rotary seal means, said ring member having one or more holes formed therein in alignment with one or more holes in said tubular sleeve through which said well fluids can drain for disposal. 
   
   
     92. The drive head of  claim 91  wherein said means for drainage additionally include lower seal means disposed in said first annulus beneath said ring member to prevent the flow of well fluids into said housing. 
   
   
     93. The drive head of  claim 92  wherein said ring member is a lantern ring. 
   
   
     94. The drive head of  claim 93  wherein said lower seal means comprise one or more ring seals. 
   
   
     95. The drive head of  claim 94  further including static seal means to seal well fluids between said polished rod and said tubular drive sleeve. 
   
   
     96. The drive head of  claim 95  wherein said tubular drive sleeve has an upper end extending through said upper opening in said housing to project above said housing for access. 
   
   
     97. The drive head of  claim 96  wherein said means connecting said tubular drive sleeve to said polished rod comprise a cap tightenably and removably connectable to said upper end of said tubular drive sleeve and a rod clamp connectable between said cap and said polished rod for transmitting rotational torque to said rod. 
   
   
     98. The drive head of  claim 97  wherein, upon removal of said cap and said rod clamp from said tubular sleeve, said static seal means, said rotary seal means, said ring member and said lower seal means are removable upwardly through said tubular drive sleeve for servicing. 
   
   
     99. A drive head for rotatably driving a polished rod in a progressing cavity pump well, comprising:
 a housing for receiving a polished rod therethrough;  
 a tubular drive shaft rotatably mounted in said housing for axially supporting and rotatably driving said polished rod, said drive shaft having an upper end extending outwardly of said housing;  
 sealing means for preventing well fluids from escaping from said well, said sealing means being accessible from the top of said drive head to facilitate servicing of said sealing means; and  
 connecting means accessible from the top of said housing for drivingly connecting said upper end of said shaft to said polished rod.  
 
   
   
     100. A drive head as defined in  claim 99 , further including:
 a tubular standpipe disposed within said drive shaft in annularly spaced relation thereto for receiving said polished rod therethrough in annularly spaced apart relation, said drive shaft and said standpipe forming an annular seal chamber;  
 said sealing means including rotary seal means disposed in said seal chamber to prevent flow of well fluids along the interior of said drive shaft; and static seal means disposed between said drive shaft and said polished rod to prevent the escape of well fluids along said polished rod.  
 
   
   
     101. A drive head as defined in  claim 100 , further including means for non-rotatably and compliantly securing a bottom end of said standpipe to said housing below a lower end of said drive shaft to permit said standpipe to tilt with respect to said drive shaft to adjust for mis-alignment of said standpipe and said drive shaft at said rotary seal means. 
   
   
     102. A drive head as defined in  claim 100 , said connecting means including a removable cap member for engaging said upper end of said drive shaft, said cap member being removable to provide access to said static seal means and said rotary seal means. 
   
   
     103. A drive head as defined in  claim 100 , said static seal means including one or more axially stacked sealing members about said polished rod and sealingly occupying an annular space between said sealing members an inner surface of said upper end of said shaft. 
   
   
     104. A drive head as defined in  claim 100 , said rotary sealing means including one or more ring seals, said ring seals sealingly engaging an inner surface of said drive shaft and an outer surface of said standpipe, and being rotatable with said drive shaft with respect to said standpipe. 
   
   
     105. A drive head as defined in  claim 104 , said rotary seal means being compression packings. 
   
   
     106. A drive head as defined in  claim 105 , further including spring means disposed in said seal chamber for compressively loading said compression packings. 
   
   
     107. A drive head as defined in  claim 100 , further including means for pressurizing said seal chamber and maintaining a fluid pressure therein above well fluid discharge pressure. 
   
   
     108. A drive head as defined in  claim 107 , said means for pressurizing including further seal means between said housing and the lower end of said drive shaft for sealing a lower end of said seal chamber; and
 means for communicating fluid under pressure to said seal chamber from a fluid pressure source.  
 
   
   
     109. A drive head as defined in  claim 108 , said further seal means including a labyrinth seal between said housing and said drive shaft. 
   
   
     110. A drive head as defined in  claim 109 , said means for communicating fluid under pressure including an oil pump and a pressure relief valve for regulating lubricating pressure supplied to said annular fluid chamber. 
   
   
     111. A drive head as defined in  claim 110 , said oil pump being driven by said drive head. 
   
   
     112. A drive head as defined in  claim 111 , said means for pressuring including means for taking fluid pressure from a hydraulic motor that drives said drive head and a pressure reducing valve for regulating said lubricating fluid pressure to said seal chamber. 
   
   
     113. A drive head as defined in  claim 100 , further including secondary rotary seal means between said drive shaft and said standpipe disposed below fluid passages extending through said drive shaft to prevent well fluid that leaks past said rotary seal means from leaking down a passage between said drive shaft and said standpipe and into drive head lubricating oil, said fluid passages allowing the well fluid to drain through the wall of said drive shaft. 
   
   
     114. A drive head as defined in  claim 113 , further including a lantern ring disposed adjacent to and in communication with said fluid passages through said drive shaft and located above said secondary rotary seal means. 
   
   
     115. A drive head as defined in  claim 114 , said secondary rotary seal means including rotary lip seals. 
   
   
     116. A drive head as defined in  claim 100 , further including means for rotatably driving said drive shaft, including an input shaft in said housing for connection to a prime mover; first gear means mounted on said input shaft for rotation therewith; and second gear means in meshing engagement with said first gear means and secured to said main shaft for rotatably driving said main shaft. 
   
   
     117. A drive head as defined in  claim 99 , further including a backspin retarder for controlling reverse rotation of said drive shaft when means for rotating said drive shaft are deactivated. 
   
   
     118. A drive head as defined in  claim 117 , said backspin retarder including a backspin retarder actuating mechanism for engaging and disengaging a brake, comprising:
 a drive member connected to said drive shaft and having at least one ball retaining groove in a lower surface, and a torque transfer ball in each groove, each groove having a ball chamber at one end for holding a ball in a disengaged position above said lower surface, a ball engaging surface at the other end of said groove and a ramped bottom surface sloping toward the lower surface from the ball chamber to the torque transfer surface; and  
 a brake actuating member freely rotatably mounted on said drive shaft below said drive member and having an upper surface juxtaposed to said lower surface and at least one ball receiving groove in said upper surface for receiving a torque transfer ball, the ball receiving groove having a ball engaging torque transfer surface at one end thereof for engaging the ball and transferring torque to the brake actuating member when the drove member rotates in a reverse direction.  
 
   
   
     119. A drive head as defined in  claim 118 , said ball receiving groove having a depth at said ball engaging surface approximately equal to the radius of a ball and sloping upwardly to said upper planar surface. 
   
   
     120. A drive had as defined in  claim 119 , said ball retaining groove having a depth at said ball chamber approximately equal to the diameter of said ball, and having a depth at said ball engaging surface approximately equal to the radius of said ball, said bottom surface thereof sloping downwardly from said ball chamber to said ball engaging surface. 
   
   
     121. A drive head as defined in  claim 120 , each said ball retaining groove having a radial hole in said drive member opening into said ball chamber, said hole having a diameter less than the diameter of said ball formed to intersect said ball chamber at approximately a height above said lower surface equal to the radius of said ball, said hole forming a ball seat on which said ball is seated when the speed of rotation of said drive shaft is at or above a threshold value. 
   
   
     122. A drive head as defined in  claim 121 , wherein, when the speed of rotation of said shaft is less than said threshold value, said ramped bottom surface is operable to push a ball along said ball receiving groove toward said torque transfer surface thereof until said ball engages said torque transfer surface. 
   
   
     123. A drive head as defined in  claim 118 , said ball being moveable into said disengaged position in said ball chamber when the forward rotational speed of said driving member exceeds a threshold value, said ball moving out of said chamber and falls toward said driven member when the rotational speed falls below said threshold and said ball engaging said torque transfer surfaces when said drive member rotates in a reverse direction. 
   
   
     124. A drive head for rotatably driving a polished rod in a progressing cavity pump well, comprising:
 a housing for receiving a polished rod therethrough;  
 a tubular drive shaft rotatably mounted in said housing for axially supporting and rotatably driving said polished rod, said drive shaft having an upper end extending outwardly of said housing;  
 a tubular standpipe disposed within said drive shaft in annularly spaced relation thereto for receiving said polished rod therethrough in annularly spaced apart relation, said drive shaft and said standpipe forming an annular seal chamber;  
 sealing means for preventing well fluids from escaping from said well, said sealing means including rotary seal means disposed in said seal chamber to prevent flow of well fluids along the interior of said drive shaft; and static seal means disposed between said drive shaft and said polished rod to prevent the escape of well fluids along said polished rod;  
 means for non-rotatably and compliantly securing a bottom end of said standpipe to said housing below a lower end of said drive shaft to permit said standpipe to tilt with respect to said drive shaft to adjust for mis-alignment of said standpipe and said drive shaft at said rotary seal means; and  
 connecting means accessible from the top of said housing for drivingly connecting said upper end of said shaft to said polished rod, said connecting means including a removable cap member for engaging said upper end of drive shaft and closing said drive shaft, said cap member being removable to provide access to said static seal means and said rotary seal means.  
 
   
   
     125. In a drive head for rotating a rod in a well having a tubular drive sleeve for fluid sealingly receiving the rod therethrough, said drive sleeve having a lower end and an upper openable end, the improvement comprising a stuffing box for said rod integrated into said upper end of said tubular sleeve to enable said stuffing box to be serviced by opening said openable upper end of said tubular sleeve, without removing said drive head from the well. 
   
   
     126. In a drive head as defined in  claim 125  wherein said stuffing box seals said rod against the pressure of fluid in the well, further including a fluid pump for pressurizing said stuffing box. 
   
   
     127. In a drive head as defined in  claim 126 , wherein said fluid pump maintains an uphole side of said stuffing box at a higher pressure than a downhole side thereof to limit leakage of fluid from said well bore.